Grapher can create a graph with data based on dates, times, or dates and times. When data are stored in the worksheet in date/time format, Grapher will automatically recognize the format and create the axis displaying the dates in most cases. By default, Grapher will use your Windows locale setting, but, different date/time formats can be used.

To create a graph from date/time data, click the Graphs | Create | <graph category> | <plot type> command. Select the data file and click Open. The appropriate axis will automatically be in date/time format.

The X axis is automatically displayed in date/time format.

If the date/time values are formatted with a custom date/time format that is not recognized by Grapher, or, you'd like to change the date/time formatting or interval, use these steps:

1. Select the axis.
2. Click on the Labels tab in the Property Manager.
3. Check the box in the General section next to Use date/time format.
4. To format the date/time labels:
   1. Click the Select button next to Major label date/time format. 
   2. Select the appropriate language in the Language (Country) list and click the Insert button. For instance, you might select German (Germany) - [$407].
   3. Select the appropriate Predefined date/time formats option and click Insert. For instance, you might select dd.MMM.yyyy.
      
   4. Click OK and the date/time format is displayed on the axis in the set format.
5. To set the interval:
   1. Click on the Ticks tab.
   2. In the Major Ticks section, check the box next to the Use date/time spacing option.
   3. Click the Every Year button next to Date/time spacing.
   4. Set the interval and units for the major tick marks. If you want a quarterly tick mark, you would increase the number in the Every box to 3 and select Month from the dropdown list.
   5. Click OK and the major tick marks are now showing the desired number of labels.
      
      

D=A+B

Where column A contains the date and column B contains the time. After adding the columns together, format the new column as a recognized date/time format. This new column can now be used to create a plot.

Updated July 26, 2019